Cod sursa(job #456507)

Utilizator alexandru92alexandru alexandru92 Data 15 mai 2010 19:50:19
Problema Flux maxim Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.32 kb
/* 
 * File:   main.cpp
 * Author: virtualdemon
 *
 * Created on May 15, 2010, 7:15 PM
 */
#include <queue>
#include <cstdlib>
#include <fstream>
#include <algorithm>
#define Nmax 1011
#define oo 0x3f3f3f3f

/*
 * 
 */
using namespace std;
int N;
int f[Nmax];
int C[Nmax][Nmax];
inline bool find_path( void )
{
    int x, y;
    queue< int > Q;
    fill( f+1, f+N+1, -1 );
    f[1]=0;
    for( Q.push(1); !Q.empty(); )
    {
        x=Q.front(); Q.pop();
        for( y=1; y <= N; ++y )
            if( -1 == f[y] && C[x][y] > 0 )
            {
                f[y]=x;
                Q.push(y);
            }
    }
    return -1 != f[N];
}
int main( void )
{
    int M, x, y, c;
    ifstream in( "maxflow.in" );
    for( in>>N>>M; M; --M )
    {
        in>>x>>y;
        in>>C[x][y];
    }
    for( x=0; find_path(); )
    {
        for( M=1; M < N; ++M )
            if( C[M][N] > 0 )
            {
                c=C[M][N];
                for( y=M; f[y]; y=f[y] )
                    if( c > C[f[y]][y] )
                        c=C[f[y]][y];
                x+=c;
                C[M][N]-=c;
                C[N][M]+=c;
                for( y=M; f[y]; y=f[y] )
                {
                    C[f[y]][y]-=c;
                    C[y][f[y]]+=c;
                }
            }
    }
    ofstream out( "maxflow.out" );
    out<<x<<'\n';
}